The present invention relates to an improved electronic filing apparatus provided with a multiple (reduction and enlargement) processing function for when various types of image data are displayed in personal computers, office computers, word processors, desk type publishing, data processing and the like.
In particular, the present invention judges whether source image data is a character and line image or a dither image such as a photograph and the like when source image data read by an image scanner into a CRT (cathode ray tube) or the like having a different degree of resolution, is multiplied and displayed and performs multiple processing using an optimum decimating method, and relates to an electronic filing apparatus for displaying an image by means of an optimum multiple processing method corresponding to the type of simultaneously read source image data.
An image data processing system for a conventional personal computer or the like uses an image scanner or the like to read image data of documents that are the object for filing display. The source data is image data that has given data compression processing and converted into binary image data. The converted image data is stored in a storage device such as an optical disk or the like and is read from the storage device in accordance with the necessity of referral or display, and is displayed on the display screen of a display means such as a CRT or the like after processing to decode the data.
The binary image data that has been read by an image scanner is stored in an image memory, and at the same time, multiple processing is performed so as to correspond to the degree of display resolution so that it can be displayed on the display screen of a display means such as a CRT or the like and transferred to the video memory.
The reason for the multiple processing described above is because it is necessary to have multiple processing corresponding to respective display devices when all binary image data read by an image scanner is to be displayed by a display means such as a CRT or the like.
The following is a description of an electronic filing apparatus using a conventional method. In this example, the description will include using a personal computer to perform read of image data from a document, the reading of the image data, the performing of multiple processing for the read image, and the final display on a CRT.
FIG. 1 is a functional block diagram showing the configuration of the major portions of an electronic filing apparatus using a conventional method. The major portions described here are an image scanner 1, an image data processing portion 2 and a display portion 3. Of these, the image data processing portion 2 comprises an image memory 2a, a multiple processing portion 2b, a video memory 2c and a disk apparatus 2d.
The image scanner 1 reads the image data into the image data processing portion 2. The image data is stored in the image memory 2a of the image data processing portion 2.
Here, for example, the degree of resolution of binary image data read by the image scanner 1 is 300.times.300 (dpi: dots per inch). When this image data is output to the display portion 3 (CRT), it is necessary to perform multiple processing to 1/(3.times.3). The multiple processing of this image data is performed by the multiple processing portion 2b. The image data for which multiple processing has been performed is transferred to the video memory 2c. This data is then displayed on the display portion 3. FIG. 2 is a flowchart for the multiple processing when there is image data display for a conventional electronic filing apparatus.
First, the (300 dpi) document image data is read by an image scanner 1 (step 201). The read image data is then stored in an image memory 2a of a image data processing portion 2 (step 202). Then, the 300 dpi image data stored in the image memory 2a is multiple processed to a display resolution of 100 dpi by either the simple decimation method or the OR decimation method (step 203). The image data that is multiple processed in step 203 is transferred to the video memory 2c and stored (step 204). It is then displayed on the CRT of the display portion 3 (step 205). The image data multiple processing of the steps 201 through 205 described above then ends.
In conventional multiple processing, either the simple decimation method or the OR decimation method is used to perform the multiple processing. In the case of simple decimation processing, when the degree of resolution is reduced by a multiple of 1/n, the n (dots).times.n (lines) of the source image data is created as data where single dots (or lines) of the image data are sampled and multiple processed to create the data. This simple decimation processing has simple multiple processing and has the merit that it can be executed in a short time. However, when the source data is continuous data such as characters or line images, fine portions are chopped and there is the problem that there are portions which are not displayed on the screen of the CRT.
On the other hand, with OR decimation processing, the data having n (dots).times.n (lines) of the source image data has single dots (or single line) calculated by OR arithmetic and multiple processing performed to create the data. This processing method differs from the simple decimation processing described above in that there is no chopping of the fine portions of characters or line images. However, when photographic images (dither images) in which the source image data uses the dither method, all of the image data for display after OR decimation processing becomes blacker (as the image is destroyed) and so it is not suitable for display on a screen.
Each of the processing methods therefore has its respective disadvantages and normally only one of the two types of multiple processing is suitable for a single electronic filing system. It is only possible for a device to be designed so that it can use only one multiple processing method. Since only one decimation processing method can be used whether the image data read by an image scanner is character, line image or some other image, or whether it is a photograph (dither image) and so it is not possible to obtain the optimum display corresponding to the type of the read image data.